DME Schematics

[rick-l]

has anyone looked at http://frwilk.com/944dme/ml31dwg.htm

Is this the same DME used in my 1988 911? It must have taken him month of
8 hour days to do this. WOW

Does anyone know what S100 a 0127 IC is? It is in the injector driver
circuit. Does that do what I think it does and charge the magnetic field
in the solenoid and return that energy to the battery? Pretty clever.

How about what is S100 a F124038-03 IC. I have access to IHS library at
work and I couldn't find anything. I'm curious how the speed sensor
works.

This is a great find. Armed with this and imaginative parts substitutions
you could repair just about anything in the DME.

[cary]

marcesq, has the whole factory DME manual. hopefully he'll see this thread and get you the info.

good luck.

[ChrisBennet]

Tim Polzin researched this, you might want to PM him if he doesn't see this thread. From the notes he sent me:

All of the semiconductors on the digital board are standard “off the self
devices” with the exception of S700 (the CPU in the 84 to 86 with custom
programming) and S100 (which is a custom op-amp which reads the flywheel
sensors and generates an angular velocity).

-Chris

[APKhaos]

The DME manual is largely a trouble shooting/testing guide. It has good schematics of the external harness and sensors, typical waveforms for the dynamic sensors, but nothing on the internals of the DME itself. My copy is courtesy of Marc.

Its a good thing, but not much help with decoding the internals. Mr Wilke has provided some of the best rference material on the Bosche Motronic that I have seen. The schematic is outstanding.

[Tim Polzin]

Yup, you won't find S100 on the shelf of your local electronics store.

S100 connects to the two flywheel sensors and creates a signal indicating angular velocity. The injectors are on a different circuit (lines 14 and 15, notice that all six injectors are tied together and fire all at once).

Most faults with DMEs fall into three catigories:

1) fatigue cracking/cold solder joints
2) results to doing stupid things (shorting ISV lines, etc.)
3) immersion in water

1 and 2 are almost always easy fixes, # 3, no.

Tim

[rick-l]

[S100 connects to the two flywheel sensors and creates a signal indicating angular velocity.]

Has anyone busted apart those two sensors? Do they consist of a coil of wire and a magnet?

[ChrisBennet]

Originally posted by rick-l
[S100 connects to the two flywheel sensors and creates a signal indicating angular velocity.]

Has anyone busted apart those two sensors? Do they consist of a coil of wire and a magnet?

They aren't obviously magnetic (like an ABS sensor). They are inductive not Hall-effect sensors.
-Chris

[Dark Lightning]

Don't mind me while I drag this thread out from the grave. ::

For a personal project on my 944T finding a source for the S100 F12438-03 chip would be extremely helpful. Aside from buying another DME to rape, what are my options?

Or is there a way to imitate what the S100 does?

Thanks in advance.